On a quiet, tree-lined street in this town with a population of just over 1,000, a lone yard sign bearing the name of Bernie Sanders serves as a faint reminder of the Vermont senator’s grassroots movement.

It is the home of Missey Bower, a special education professional, who cast her vote for Sanders in the Pennsylvania Democratic primary and helped the senator carry the working-class Wyoming County in which her modest, one-storey home sits across from a public library.

But it was Hillary Clinton who claimed victory in the state and ultimately the contest for the Democratic party’s presidential nomination. And Bower is precisely the kind of voter Clinton must still persuade in her favor with 81 days remaining until election day.

Hours after the former secretary of state rallied with Joe Biden in neighboring Scranton, the vice-president’s hometown where Clinton also has roots, Bower said she is watching closely as the Democratic nominee campaigns on a progressive agenda while simultaneously making direct overtures to the Republicans and center-right independents who cannot fathom voting for Donald Trump.

Her concern, like many Sanders supporters, is whether his radical platform taking on Wall Street and corporate interests, and offering free college tuition, will be discarded as she courts Republicans.

Bower is “terrified” of a Trump presidency but voiced concerns with Clinton’s balancing act.

“I think she’s saying what she needs to say to pull people from Trump, which is a good thing,” she said, “but I don’t know when she’s being sincere and when she’s just doing what she needs to in order to get elected.

“I just feel like she’s been in the system for so long, how could she not be part of the system?”

Her campaign has trumpeted endorsements from prominent Republicans, including national security officials and prolific donors. Appearing on behalf of his wife last week, Bill Clinton fielded a question on how she could be trusted by citing her support from former aides to George W Bush and Ronald Reagan.

The rationale is clear: given Trump’s erratic behavior and history of offensive rhetoric toward minorities and women, the election is much broader than a choice of policies. As framed by Clinton’s campaign, it is a battle for the principles upon which America was founded, in which the question facing voters is whether they would hand the Oval Office to a candidate deemed by members of his own party as fundamentally unfit to lead the nation.

It was precisely this message that Biden and Clinton brought with them to a sports facility in Scranton this week, with the vice-president telling more than 3,000 supporters Trump was “totally, thoroughly unqualified” to assume the role of commander-in-chief.

Down the road, at a local coffee shop often frequented by Sanders supporters, a pair of young voters debated whether the anti-Trump missive was enough for them to cast their ballots for Clinton.

“One of my issues is she tries to appeal to both left and right at the same time, and that’s difficult because it’s so polarized right now,” said Anna Salerno, a 20-year-old native of Scranton who attends college in New York.

Seated across from her was Willie Demyan, a 21-year-old college graduate who characterized Clinton as embracing “more of a political strategy” that left him questioning whether she was committed to a liberal platform.

“That’s what I liked about Bernie, he might seem monotonous,” he said, before Salerno completed the sentence for him: “But you knew he wasn’t going to waver on it.”

Salerno nonetheless said she planned to vote for Clinton to shut Trump out of the White House, while Demyan had yet to be convinced.

While laying out her agenda at the Democratic national convention in Philadelphia last month, Clinton vowed to champion many of the issues injected into the race by Sanders and his progressive base of supporters.

From campaign finance reform and raising the minimum wage to providing debt-free college and regulating Wall Street, the blueprint she provided while accepting the Democratic party’s nomination – and has carried with her to the stump – remains very much in line with promises made while tacking left in the primary.

If there is any movement toward the center, it appears to be less in substance than it is in tone. Trump, put simply by Clinton, is a threat to American democracy.

The argument is resonating, with Clinton opening up a double-digit lead in several key battleground states in recent weeks. In Pennsylvania, one new poll found her holding a 10-point advantage over Trump – undercutting the real estate mogul’s efforts to seek out a pathway to the presidency in America’s blue-collar rust belt.

Clinton nonetheless implored Democrats at a voter registration event in west Philadelphia on Tuesday not to underestimate the stakes ahead.

And even as some liberal groups are maintaining a watchful eye on the direction of her campaign, the majority of Sanders supporters have already shifted their allegiance to Clinton according to most polling.

On Tuesday, she also received the endorsement of the Working Families party, an organization dedicated to advancing progressive policy that previously backed Sanders. “The change we need next year starts with electing Secretary Clinton, but it doesn’t end there,” Dan Cantor, the group’s national director, said.

“We know we won’t always agree, and we’re ready to work hard to press her to deliver on the economic, environmental and racial justice promises she made during the campaign.”

Sean Cutkelvin, a college student working behind the counter at the Northern Lights coffee shop, where Sanders supporters often dwell, said he was confident Clinton would pursue progressive priorities. The 21-year-old, who voted for Sanders in the Pennsylvania primary, said friends had accused him of selling out when they learned he was now supporting Clinton.

“I told them there is no other candidate,” he said. “In the other party, there’s fear mongering, there’s hatred.